期刊
JOURNAL OF BIOLOGICAL CHEMISTRY
卷 289, 期 46, 页码 32353-32363出版社
AMER SOC BIOCHEMISTRY MOLECULAR BIOLOGY INC
DOI: 10.1074/jbc.M114.603506
关键词
Atomic Force Microscopy (AFM); Fluorescence Resonance Energy Transfer (FRET); hERG; Molecular Imaging; Protein Complex; Sigma Receptor
资金
- Kidney Research UK
- CNRS
- University of Nice Sophia Antipolis
- Association Ti'Toine Normandie
- Kidney Research UK [RP17/2012] Funding Source: researchfish
The sigma-1 receptor is an endoplasmic reticulum chaperone protein, widely expressed in central and peripheral tissues, which can translocate to the plasma membrane and modulate the function of various ion channels. The human ether-a-go-go-related gene encodes hERG, a cardiac voltage-gated K+ channel that is abnormally expressed in many human cancers and is known to interact functionally with the sigma-1 receptor. Our aim was to investigate the nature of the interaction between the sigma-1 receptor and hERG. We show that the two proteins can be co-isolated from a detergent extract of stably transfected HEK-293 cells, consistent with a direct interaction between them. Atomic force microscopy imaging of the isolated protein confirmed the direct binding of the sigma-1 receptor to hERG monomers, dimers, and tetramers. hERG dimers and tetramers became both singly and doubly decorated by sigma-1 receptors; however, hERG monomers were only singly decorated. The distribution of angles between pairs of sigma-1 receptors bound to hERG tetramers had two peaks, at approximate to 90 and approximate to 180 degrees in a ratio of approximate to 2:1, indicating that the sigma-1 receptor interacts with hERG with 4-fold symmetry. Homogeneous time-resolved fluorescence (HTRF (R)) allowed the detection of the interaction between the sigma-1 receptor and hERG within the plane of the plasma membrane. This interaction was resistant to sigma ligands, but was decreased in response to cholesterol depletion of the membrane. We suggest that the sigma-1 receptor may bind to hERG in the endoplasmic reticulum, aiding its assembly and trafficking to the plasma membrane.
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